Journal of Tropical Oceanography ›› 2023, Vol. 42 ›› Issue (1): 87-97.doi: 10.11978/2022099CSTR: 32234.14.2022099

Special Issue: 全球变化专题

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The effects of ocean acidification and warming on the growth and calcification in coralline alga Porolithon cf. onkodes

YANG Fangfang1,2,3(), XIAO Zhiliang1,4, WEI Zhangliang1,2,3, HUANG Yi1,4, LONG Lijuan1,2,3()   

  1. 1. Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    2. Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
    3. CAS Tropical Marine Biological Research Station in Hainan, South China Sea Institute of Oceanology, Sanya 572000, China
    4. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-05-05 Revised:2022-06-02 Online:2023-01-10 Published:2022-06-15
  • Contact: YANG Fangfang, email: ycuyang@scsio.ac.cn;LONG Lijuan, email: longlj@scsio.ac.cn
  • Supported by:
    National Natural Science Foundation of China(42176157); Key Programs of the Chinese Academy of Sciences(ZDRW-XH-2021-2-06); Major Project of Talent Team introduction for Guangdong Provincial Laboratory of Southern Marine Science and Engineering (Guangzhou)(GML2019ZD0402); Strategic Priority Research Program of the Chinese Academy of Sciences(XDA13020203)

Abstract:

Calcified macroalgae, an important calcifying group widely distributed in reef ecosystems, plays vital roles in the primary productivity and reef frameworks construction. Furthermore, several species of calcified algae can induce the coral larval settlement, which is closely related to the sustained development of coral reef ecosystem. However, it is not clear how calcified algae will response to ocean acidification and warming. In this study, healthy and bleached Porolithon cf. onkodes were exposed to different pCO2 (400 µatm, 1200 µatm, 1800 µatm) and temperatures (27 ℃, 30 ℃, 32 ℃) for one month, respectively. The results showed that the growth rate and net calcification rate of living P. onkodes were not significantly affected when the temperature increased from 27 ℃ to 30 ℃, however, these physiological parameters declined significantly at 32 ℃. The net calcification rate decreased from 206.99 nmol·cm-2·h−1 (400 µatm pCO2 + 27 ℃) to -42.22 nmol·cm-2·h−1 (1200 µatm pCO2 + 32 ℃). Similarly, the enhancement of pCO2 also significantly inhibited the growth and calcification in living P. onkodes. Additionally, warming and acidification had interactive effects on the chlorophyll a content and net calcification rate. Compared with living P. onkodes, dead or bleached algal skeletons were more susceptible to warming and acidification. When the temperature was 30 ℃ or the pCO2 was 1200 µatm, the net dissolution rate of dead algal skeletons increased significantly. Furthermore, the adverse effects of warming were exacerbated when high temperatures coincided with acidification. The results revealed that acidification and warming not only affected the growth and calcification rates of living algae, but also accelerated the dissolution rate of calcium carbonate skeleton, which can affect the coral reef ecosystem. The study may contribute to predict the impacts of climate change on reef ecosystem to protect reef ecosystems.

Key words: ocean acidification, warming, Porolithon cf. onkodes, calcification, growth, coral reef ecosystems